GEOM_PART: integrity check failed (mirror/gm0, MBR) on FreeBSD 8.3-RELEASE

[Mark Knight]

I just did a source upgrade from 8.2 to 8.3.  System boots but has this 
warning:

	GEOM_PART: integrity check failed (mirror/gm0, MBR)

Google points to issues with FreeBSD 9 and the need to migrate to GPT 
but I wasn't expecting this with 8.3!

Are there any quick fixes to eliminate this warning or is it safe to 
ignore please?

sudo gpart list:

Geom name: mirror/gm0
modified: false
state: CORRUPT
fwheads: 255
fwsectors: 63
last: 976773166
first: 63
entries: 4
scheme: MBR
Providers:
1. Name: mirror/gm0s1
    Mediasize: 500107829760 (465G)
    Sectorsize: 512
    Stripesize: 0
    Stripeoffset: 32256
    Mode: r2w2e3
    attrib: active
    rawtype: 165
    length: 500107829760
    offset: 32256
    type: freebsd
    index: 1
    end: 976773167
    start: 63
Consumers:
1. Name: mirror/gm0
    Mediasize: 500107861504 (465G)
    Sectorsize: 512
    Mode: r2w2e5

Geom name: mirror/gm0s1
modified: false
state: OK
fwheads: 255
fwsectors: 63
last: 976773104
first: 0
entries: 8
scheme: BSD
Providers:
1. Name: mirror/gm0s1a
    Mediasize: 498597888000 (464G)
    Sectorsize: 512
    Stripesize: 0
    Stripeoffset: 32256
    Mode: r1w1e1
    rawtype: 7
    length: 498597888000
    offset: 0
    type: freebsd-ufs
    index: 1
    end: 973823999
    start: 0
2. Name: mirror/gm0s1b
    Mediasize: 1509941760 (1.4G)
    Sectorsize: 512
    Stripesize: 0
    Stripeoffset: 381713920
    Mode: r1w1e0
    rawtype: 1
    length: 1509941760
    offset: 498597888000
    type: freebsd-swap
    index: 2
    end: 976773104
    start: 973824000
Consumers:
1. Name: mirror/gm0s1
    Mediasize: 500107829760 (465G)
    Sectorsize: 512
    Stripesize: 0
    Stripeoffset: 32256
    Mode: r2w2e3
-- 
Mark A. R. Knight                               finger: markk at knigma.org
Tel: +44 7880 556751                            http://www.knigma.org/